Improved diagnosis of unilateral renal artery lesions after captopril administration.

Captopril was administered (1 mg/kg of body weight) to 37 unselected hypertensive patients undergoing bilateral renal vein catheterization to determine its safety and efficacy in diagnosing hypertension related to unilateral renal artery lesions. In the 18 patients who had a unilateral renal artery lesion demonstrated by angiography, the ratio of plasma renin activity of the involved to uninvolved renal vein rose significantly after administration of captopril, whether or not patients were taking antihypertensive medication. This postcaptopril ratio differentiated cases of unilateral lesions from cases of bilateral lesions or absence of lesions without any overlap. The test was well tolerated despite occasional large drops in blood pressure. These data show that converting enzyme inhibition increases the diagnostic accuracy of renal vein catheterization by increasing the difference between the amount of plasma renin secreted by the two kidneys in cases of unilateral renal artery lesions.